essential questions: what are the processes by which different atoms come together to form new...
TRANSCRIPT
Ionic Bonding
New Unit: Chemical Bonding
Essential Questions:
What are the processes by which different atoms come together to form new compounds and what forces hold solutions of these compounds/molecules together?
Ions
An atom with a charge Positive: cation Negative: anion
How do these atoms become charged?
Valence Electrons
Electrons in the highest occupied energy level
The number of valence electrons greatly determines chemical properties of an element and how it will react
How can we find the number of valence electrons in an element?
By using electron configurations
Electron configuration for chlorine:
1s22s22p63s23p5
What is the highest energy level reached? 3
How many electrons are there? 7
Because of trends, we can also use group numbers!
Looking at the electron configuration for elements in the same group, they will all have the same number of valence electrons (just the A groups though! Not the B groups.)
Guided Practice on Valence Electrons
How many valence electrons are there in the following elements?
ChlorineCalciumAluminum CarbonNeon
Electron Dot Structures
Also known as Lewis Structures Diagrams that represent the number
of valence electrons in the atom
1. Find number of valence electrons2. Write element symbol3. Fill valence electrons around symbol,
one on each side first then double up
Guided Practice on Lewis Structures
Find the Lewis Dot Structures for the following elements:
ChlorineCalciumAluminum CarbonNeon
Octet Rule
Noble gases are the most stable elements on the Periodic Table due to the fact that they have 8 valence electrons (a complete outer shell)
Atoms will either lose or gain electrons through bonding in order to attain those complete 8 configurations Metal elements tend to lose electrons
while nonmetals tend to gain
Forming ions
How do cations form? Losing valence electrons▪ Who tends to form cations?
How do anions form? Gaining valence electrons ▪ Who tends to form anions?
Forming cations
Metals Lose valence electrons
Example: Calcium Normal calcium calcium ion
20 protons 20 protons20 electrons 18 electronsno charge +2 charge
Forming anions
Nonmetals Gain electrons to get to an octet
Example: Chlorinenormal chlorine chlorine ion
17 protons 17 protons
17 electrons 18 electronsno charge -1 charge
Independent Practice
Formation of Ionic Compounds
Composed of a cation and an anion Held together by ionic bonds Represented by a chemical formula A formula unit is the lowest whole-
number ratio of ions in an ionic compound
Formation of Ionic Compounds
When writing the formulas, use the criss-cross method
Mg+2 Cl-1
MgCl2
Showing Ionic Bonding with Lewis Structures
Showing Ionic Bonding with electron configurations
Guided Practice on Ionic Compound Formulas
For the following pairs of elements, write the formula for the ionic compound formed
Aluminum and ChlorineSodium and SulfurNitrogen and fluorine
Independent Practice